• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.10B
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• pp.619-629
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• 2005

In this paper, we propose energy-aware routing schemes which are simple enough to be applicable to the wireless sensor networks. The one hop upstream no de in direction of the base-station is determined in four different ways based on the energy information of neighboring nodes, which are obtainable via the process of self-organization of the network. The fair distribution of the energy consumption over all the possible routes to the base-station is one of the design objectives. Also, an alternate route search mechanism is proposed to cope with the situation in which no routing information is available due to lack of remaining energy of the neighboring nodes. The mechanism turns out to be a supplementary scheme to improve the energy efficiency. Lots of simulations are performed to examine the performance metrics such as the energy efficiency, throughput, network lifetime, and the transmission latency of the proposed schemes. Simulation results show the feasibility of the simple routing schemes for the sensor networks.

• Journal of the Korea Society of Computer and Information
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• v.27 no.5
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• pp.117-125
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• 2022

Recently, as users' interest for travel increases, research on a travel route recommendation service that replaces the cumbersome task of planning a travel itinerary with automatic scheduling has been actively conducted. The most important and common goal of the itinerary recommendations is to provide the shortest route including popular tour spots near the travel destination. A number of existing studies focused on providing personalized travel schedules, where there was a problem that a survey was required when there were no travel route histories or SNS reviews of users. In addition, implementation issues that need to be considered when calculating the shortest path were not clearly pointed out. Regarding this, this paper presents a quantified method to find out popular tourist destinations using social big data, and discusses problems that may occur when applying the shortest path algorithm and a heuristic algorithm to solve it. To verify the proposed method, 63,000 places information was collected from the Gyeongnam province and big data analysis was performed for the places, and it was confirmed through experiments that the proposed heuristic scheduling algorithm can provide a timely response over the real data.

• Journal of Industrial Technology
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• v.22 no.A
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• pp.73-82
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• 2002

It is difficult to find the shortest paths using existing algorithms (Dijkstra, Floyd-Warshall algorithm, and etc) in high complex and large size real traffic networks The objective of this paper is to develop an evolution program to find the multiple shortest paths within reasonable time in these networks including turn-restrictions, U-turns, and etc.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.11a
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• pp.758-760
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• 2013

위치기반 서비스에 관련된 기술 연구가 활발히 진행됨에 따라 다수의 사용자가 위치기반 앱 서비스를 이용하고 있다. 그러나 위치기반 앱 서비스를 이용하는 사용자가 점차 증가함에 따라 사용자의 위치정보가 노출될 확률이 높아지고 있다. 우리는 개인의 위치 정보를 보호하면서도 서버의 작업 부하를 줄일 수 있는 self-Privacy Protection Range (self-PR)을 제안한다. Self-PR은 클라이언트의 조건(ex. 배터리 상태, 모바일 기기의 성능 등)에 따라 보호 영역을 설정할 수 있기 때문에 이상적인 질의처리가 가능하다. 반면에 서버는 클라이언트의 self-PR이 증가할수록 서버는 데이터 탐색 경로가 짧아지기 때문에 작업부하를 줄일 수 있다. 그리고 서버는 클라이언트의 self-PR 확인하고 질의 결과를 전송하기 때문에 정확한 질의 결과를 전송할 수 있다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.1
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• pp.126-132
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• 2011

In the application areas of LBS(Location Based Service) and ITS(Intelligent Transportation System), continuous k-nearest neighbor query(CkNN) which is defined as a query to find the nearest points of interest to all the points on a given path is widely used. It is necessary to acquire results quickly in the above applications and be applicable to spatial network databases. It is also able to cope successfully with frequent updates of POI objects. This paper proposes a new method to search nearest POIs for moving query objects on the spatial networks. The method produces a set of split points and their corresponding k-POIs as results with partial order among k-POIs. The results obtained from experiments with real dataset show that the proposed method outperforms the existing methods. The proposed method achieves very short processing time(15%) compared with the existing method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.4
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• pp.914-925
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• 1998

This paper considers the evaluation of the hybrid acquistion perdformance for the pilot signal in the direct sequence code division multiple access(DS/CDMA) forward link. the hybrid acquisition is introduced by the combination of two schemes, the parallel and serial acquisions. The mean acquisition time of the proposed scheme is derived to consider both the best case(the correct code-phase offsets are included i one subset) and the worst case(the correct code-phase offsets exist at the boundary of two subsets), which are cause by the distribution of the correct code-phase offsets in the subset. Expressions for the detection, false alarm, and miss probabilities are derived for the case of multiple correct code-phase offsets and multipath Rayleigh fading channel. Numerical results present the hybrid acquistion performance with repect to design parameters such as postdetectio integration length in the search and verification modes, subset size, and number of I/Q noncoherent correlators, and compare the hybrid acquistion with the parallel acquistion in terms of the minimum acquistion time under the same hardware complexity.

• Journal of the Korean Association of Geographic Information Studies
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• v.26 no.3
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• pp.85-96
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• 2023

This study developed and evaluated a safe route guidance service for electric personal assistive mobility device used mainly by the mobility impaired people to improve their mobility. Thirteen underlying factors affecting the mobility of electric personal assistive mobility device have been derived through a survey with the mobility impaired people and employees in related organizations in Busan Metropolitan City. After assigning safety scores to individual factors and identifying the relevant factors along routes of interest with an object detection AI model, the safe route for electric personal assistive mobility device was provided through an optimal path-finding algorithm. As a result of comparing the general route of T-map and the recommended route of this study for the identical routes, the latter had relatively fewer obstacles and the gentler slope than the former, implicating that the recommended route is safer than the general one. As future works, it is necessary to enhance the function of a route guidance service based on the real-time location of users and to conduct spot investigations to evaluate and verify its social acceptability.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.7
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• pp.870-874
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• 2018

In the worst maritime accidents, people should abandon ship, but ship structures are narrow and complex and operation takes place on rough seas, so escape is not easy. In particular, passengers on cruise ships are untrained and varied, making evacuation prospects worse. In such a case, the evacuation management of the crew plays a very important role. If a rescuer enters a ship at distress and conducts rescue activities, which zones represent the most effective entry should be examined. Generally, crew and rescuers take the shortest route, but if an accident occurs along the shortest route, it is necessary to select the second-best alternative. To solve this situation, this study aims to calculate evacuation routes using Q-Learning of Reinforcement Learning, which is a machine learning technique. Reinforcement learning is one of the most important functions of artificial intelligence and is currently used in many fields. Most evacuation analysis programs developed so far use the shortest path search method. For this reason, this study explored optimal paths using reinforcement learning. In the future, machine learning techniques will be applicable to various marine-related industries for such purposes as the selection of optimal routes for autonomous vessels and risk avoidance.

• KIPS Transactions on Computer and Communication Systems
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• v.11 no.8
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• pp.269-280
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• 2022

With the rise of a decentralized finance market (so called, DeFi) using blockchain technology, users and capital liquidity of decentralized finance applications are increasing significantly. The Automated Market Maker (AMM) is a protocol that automatically calculates the asset price based on the liquidity of the decentralized trading platform, and is currently most commonly used in the decentralized exchanges (DEX), since it can proceed the transactions by utilizing the liquidity pool of the trading platform even if the buyers and sellers do not exist at the same time. However, Automated Market Maker have some disadvantages since the cost efficiency of each transaction using Automated Market Maker depends on the liquidity size of some liquidity pools used for the transaction, so the smaller the size of the liquidity pool and the larger the transaction size, the smaller the cost efficiency of the trade. To solve this problem, some platforms are adopting Transaction Path Routing Algorithm that bypasses transaction path to other liquidity pools that have relatively large size to improve cost efficiency, but this algorithm can be further improved because it uses only a single transaction path to proceed each transaction. In addition to just bypassing transaction path, in this paper we proposed a Multi-Path Routing Algorithm that uses multiple transaction paths simultaneously by distributing transaction size, and showed that the cost efficiency of transactions can be further improved in the Automated Market Maker-based trading environment.

• Journal of Korean Society of Transportation
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• v.26 no.3
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• pp.233-243
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• 2008

Recognition for the importance and roles of public transportation is increasing because of traffic problems in many cities. In spite of this paradigm change, previous researches related with public transportation trip assignment have limits in some aspects. Especially, in case of multimodal public transportation networks, many characters should be considered such as transfers. operational time schedules, waiting time and travel cost. After metropolitan integrated transfer discount system was carried out, transfer trips are increasing among traffic modes and this takes the variation of users' route choices. Moreover, the advent of high-technology public transportation card called smart card, public transportation users' travel information can be recorded automatically and this gives many researchers new analytical methodology for multimodal public transportation networks. In this paper, it is suggested that the methodology for establishment of brand new multimodal public transportation networks based on computer programming methods using transportation card data. First, we propose the building method of integrated transportation networks based on bus and urban railroad stations in order to make full use of travel information from transportation card data. Second, it is offered how to connect the broken transfer links by computer-based programming techniques. This is very helpful to solve the transfer problems that existing transportation networks have. Lastly, we give the methodology for users' paths finding and network establishment among multi-modes in multimodal public transportation networks. By using proposed methodology in this research, it becomes easy to build multimodal public transportation networks with existing bus and urban railroad station coordinates. Also, without extra works including transfer links connection, it is possible to make large-scaled multimodal public transportation networks. In the end, this study can contribute to solve users' paths finding problem among multi-modes which is regarded as an unsolved issue in existing transportation networks.